Submergible drilling rig foundation and method of constructing same



Feb. 6, 1951- J. T. HAYWARD Y 2,540,373

SUBMERGIBLE DRILLING RIG FOUNDATION Q 7 J AND METHOD 0F CQNSTRUCTING SAME N Filed Aug. 1'7, 1948 7 She ets-She'et 1 c/ohn I Hayward INVENTOR.

ATTORNEY Feb. 6, 1951 J. T. HAYWARD 2,540,878

SUBMERGIBLE DRILLING RIG FOUNDATION AND METHOD OF CONSTRUCTING SAME Filed Aug. 17, 1948 7 Sheets-Sheet 2 I I I l I v 1 l I g a I a I l O I II l 'J w John 7. Hayward INVENTOR.

INVENTOR.

7 Sheets-Sheet 3 (Jo/m 7.' Hayward ATTORNEY HAYWARD J. T. SUBMERGIBLE DRILLING RIG FOUNDATION .AND METHOD OF CONSTRUCTING SAME Feb. 6, 1951 Filed. Aug 17, 1948 J. T. HAYWARD SUBMERGIBLE DRILLING RIG FOUNDATION Feb.6, 1951 AND METHOD OF CONSTRUCTING SAME '7 Sheets-Sheet 4 Filed Aug. 17, 1948 QM, I N 2 %N F L n l I l w. mw l @l. I I III H H I H MN I Ilia- II N a 3 3 ww MN (John 7.' Hayward INVENTOR.

A T TOR/VEV Feb. 6, 1951 J. T. HAYWARD SUBMERGIBLE DRILLING RIG FOUNDATION AND METHOD OF CONSTRUCTING SAME Filed Aug. 17, 1948 7 Sheets-Sheet 5 I l l (lo/2 71 Hayward INVENTOR.

A TOR/VF) Fiie'd Aug. 17,1948v Feb. 6, 1951 I J. T. HAYWARD I I SUBMERGIBLE DRILLING RIG FOUNDATION v.mmmz'rnon 0F CONSTRUCTING SAME V I Q '7 Sheets-Sheet 6 I ;24 24 2a @2 7 E INVEN TOR.

A r TOR/V5) Feb. 6, 1951 J. T. HAYWARD 2,540,873 SUBMERGIBLE D LING RIG FOUNDA N AND METHO CONSTRUC D TING S Filed Aug. 17, 1948 7 Sheets-Sheet 7 ATTORNEY Patented Feb. 6, 1951 UNITED STATES- PATENT OFFICE SUBMERGIBLE DRILLING RIG FOUNDATION AND METHOD OF CONSTRUCTING SAME 16 Claims.

This invention relates to a submergible foundation for a drilling rig for the drilling of wells at water locations and to the method of constructing the same, and particularly to a drilling barge which may be completely submerged to the bottom underlying a water body to provide a firm foundation for a drilling rig and which may be raised from the bottom and removed when drilling is completed.

The drilling of oil wells in off-shore locations, such as on the Continental Shelves along the coasts of the United States in water depths greater than about 15 feet, is increasing greatly in importance and creates many new and serious prob lems in providing both economical and firm and safe support for the heavy drilling rigs employed. Since such locations may be many miles from the shore, open ocean conditions will normally prevail, including often severe wind and wave conditions, which make for great expense and difliculty in transporting and erecting conventional drilling rig foundations which are adequate to meet the conditions encountered.

Drilling barges have heretofore been employed with considerable success for drilling at water locations where water depths are generally substantially less than about fifteen feet, that is, depths which are sufficiently shallow so that the barge hull need be only partially submerged to bring it to rest upon the bottom. At greater water depths, such barges would present large surfaces which would be subjected to such buffeting by the winds and waves prevailing in open ocean areas as to cause shifting of the barge over the water bottom, and serious damage to the barge and the equipment mounted thereon. Moreover the instability of such barge structures, due to the heavy drilling equipment mounted thereon, may lead to capsizing while afloat, and to very dangerous tilting during drilling and while on bottom.

Accordingly, the present invention has for its principal objects the provision of a novel form of submerged foundation for drilling rigs, and the method of constructing the same, which is particularly adapted for use in off-shore waters of greater depth than heretofore considered feasible or practical for the employment of conventional drilling barges.

In accordance with one embodiment of this invention, a form of barge structure is provided which is adapted to be completely submerged beneath the surface of the water in the open ocean, whereby to avoid exposure of solid areas to the buffeting action of wind and wave normally prevailing in such areas, and to thereby provide a firm foundation for the drilling rig. The barge structure comprises a, novel arrangement which includes a main hull section which is fully submergible and on which the drilling rig and derrick may be permanently mounted, and a pair of stabilizing pontoon elements of controllable buoyancy arranged in parallel on opposite sides of the main hull section by means of which the stability of the main hull section may be effectively controlled and maintained at all times. The pontoon elements are also adapted to be fully submerged alongside the main hull section after the latter has come to rest on bottom to thereby increase the foundation area for the drilling rig and to protect the main hull section against erosion and washing out of the underlying land bottom by the action of currents in the water and to prevent tilting during drilling operations.

Other and more specific objects and advantages of this invention will become apparent from the following detailed description when read in conjunction with the accompanying drawings which illustrate one useful embodiment in accordance with this invention.

In the drawings:

Figs. 1 and 2, taken together, comprise a side elevation of a barge structur in accordance with this invention;

Fig. 8 is a plan view of the main barge section and supplementary pontoons and their interconnecting elements, which together comprise the principal elements of the novel barge structure;

Figs. 4 and 4a are partial cross-sectional elevations taken generally along line 44 of Fig. 1 looking aft of the structure therefrom and illustrating in a comparable manner the relative positions of the parts thereof at two different stages of submergence;

Figs. 5 and 5a are views similar to Figs. 4 and 4a looking aft from line 5-5 of Fig. 4; and

Figs. 6, 7, 8 and 9 are generally schematic end views illustrating the relative positions of the main barge and stabilizing pontoons at several stages of operation.

As illustrated in the drawings, the barge structure comprises a main hull ll) of generally rectangular form. An elongated slot H (see Fig. 3) extends centrally of the hull from the forward end to a point well toward the mid-ship portion of the hull, providing a vertical opening through the hull through which drilling operations may be conducted in the land beneath the hull. An open-work steel super-structure l2 extends upwardly from the upper deck I3 of the hull and is 3 adapted to support thereon, at a suitable height above the hull deck, suitable working platforms Na and a conventional drilling derrick i4, the center of which is located generally above the inner end of slot ii. A housing I! is also mounted on super-structure l2 aft of derrick i4, and is adapted to enclose the engines and other machinery employed in connection with the drilling Ill and arranged for vertical movement relative to hull l0. Pontoons l'I-l 1 are preferably arranged alongside hull H) in such positions that a substantial portion of the inner end of slot II is enclosed between the forward portions of the pontoons. The latter, like hull ID, are suitably compartmented, as indicated by the broken lines H3 in Fig. 3, and are likewise provided with suitable and conventional filling and emptying gear (not shown) for controlling their buoyancy. Pontoons l'l-il are connected together at longitudinally spaced points by means of beams l9l9 which extend transversely across the deck of hull l and have their outer ends rigidly connected to the upper decks of pontoons l1--i|. Spacing pads 20 (see Figs. 1, 2, and 5a) of suitable height are interposed between the pontoon decks and the ends of beams i9 to provide suitable spacing therebetween for purposes to be hereinafter described. With this arrangement, it will be seen that the pontoons together with beams i9 form a relatively rigid unitary structure which may engage in vertical movement relative to the hull in but in which the pontoons are held by their connection to beams i9 against appreciable lateral movement relative to the hull. The connections of the pontoons to beams i3 are so arranged as to provide a degree of clearance between the adjacent sides of the pontoons and hull l0 suflicient to prevent binding engagement therebetween during relative movement. The inner side walls 2| of the pontoons will preferably be sloped outwardly and downwardly relative to the sides of the hull to provide a downwardly diverging opening therebetween in order to prevent the acccumulation or lodgement of sand or other detritus between these elements which might otherwise prevent freedom of relative longitudinal movement between them during the submerging and raising operations to be described hereinafter. Pairs of spaced parallel vertical columns 22--22 (see Figs. 1 and 3) extend upwardly from deck l3 on opposite sides of hull I0 and enclose between them one of the beams I9 to provide guides for guiding the vertical movement of the beams and the attached pontoons relative to hull i0, and to attach the pontoons to the hull. It will be understood that more than two transverse beams I9 may be employed, if desired, to connect the pontoons as described. However, two beams will ordinarily be found to be suflicient for this purpose and, as illustrated (see Fig. 3 particularly) both are located aft of the inner end of slot H in order not to interfere with the drilling operations which are conducted through and over the slot.

At opposite ends of each of the pontoons, structural pads 23-23 are mounted to extend above the decks thereof and above the level of beams i3. Pads 23 are adapted to cooperate with cantilever arms, indicated generally by the numerals 24 (see Figs. 1, 2, 4, 4a), which extend at right angles from the sides of super-structure l2 at suitably spaced points longitudinally thereof to place the arms in vertical registration with pads 23. Arms 24 are positioned at a suitable height on super-structure I2 such that when hull I0 and pontoons 11 are in the normal towing position (Figs. 1, 2 and 6), or both are in the fully submerged positions (see Figs. 4 and 9) arms 24.will be vertically spaced from pads 23. Arms 24 are adapted to limit the relative vertical movement between hull I0 and pontoon I I for purposes to be hereinafter described.

Each of the arms 24 comprises a pair of vertically positioned, spaced, parallel, structural plate members 2'525, each of which has its inner vertical edge connected by a pair of vertically spaced hinges 2626 to the side of super-structure l2, whereby each of the plate members may be swung to lie flat against the side of the superstructure. (See Fig. 3). Removable connectors 21 (see Figs. 1 and 2) tie each of the pairs of plate members 25 together to form a relatively rigid structure comprising each of the arms 24. Shafts 28 extend vertically from the upper decks of the pontoons through each of the pads 23 into the space between each of the pairs of members 25 and are movable vertically therebetween in response to relative vertical movement between pontoons l1 and hull l0 and serve a purpose to be hereinafter described.

The above described barge structure is operated in the following manner, reference being had particularly to Figs. 6 to 9, inclusive. Fig. 6 illustrates the relative positions of hull l0 and pontoons I! when these parts are afloat in the normal towing position. It will be noted that at this stage the buoyancy of the hull and pontoons will be regulated so that substantial portions of these members are well above the surface of the water, indicated at 29, the bottoms of these members being well above the land bottom, indicated at 30. It will also be noted that, at this stage, arms 24 are elevated well above the tops of pads 23 and that beams l9 are above the deck of hull i0. It is desirable that in the towing position the pontoons be rigidly interconnected withthe hull so that they may increase the stability by increasing the beam (width) of the combination and also because, by supporting a portion of the weight of the main hull and superstructure, the draught of the latter may be reduced during towing. For this purpose, cross-pieces 2211 (see Figs. 1, 3, 5 and 6) are rigidly bolted to column 22 while beams i9 are in turn rigidly bolted to these cross-pieces. It will be evident that under these conditions the two pontoons and the main hull become one single vessel from the point of view of stability.

Fig. 7 illustrates the first stage of operations after the structure has reached the drilling location and submergence has begun. Beams i9 will be unbolted from cross-pieces 22a and the latter, in turn, unbolted from columns 22 and stored for further use. The pontoons may be partially flooded to assist this operation. Water ballast will then be introduced into the compartments of hull I0 causing the hull to initiate its submergence, while the buoyancy of pontoons I1 is being increased by de-watering. Hull III will, therefore, descend relative to the pontoons carrying arms 24 correspondingly downwardly toward the tops of pads 23. The normal spacing between pads 23 and arms 14 will be dimensioned to cause arms 24 to come in contact with pads 23 well before deck l3 of hull l sinks to the water level. The contact of arms 24 with pads 23 will immediately transfer at least a part of the load of the structure to pontoons ll which, at this moment are maintained in positively buoyant condition and will, therefore, maintain stability during further submersence of the hull. Ballast will now be introduced into pontoon compartments as additional ballast is introduced into hull I0, whereby both the hull and pontoons now continue to submerge together while maintaining their relative elevations, with the result that when the upper deck of hull l0 sinks below the surface, the most critical stage of the submergence, a substantial portion of the pontoons will still be above the water thereby maintaining the meta-centric height at a safe value and thereby keep the structure fully stabilized. Submergence of the pontoons and hull will now be continued until the bottom of hull l0 comes to rest on land bottom 30, as illustrated in Fig. 8. It will be understood that the several parts of the structure will be so dimensioned relative to each other and to the depth of the water in which the structure is to be submerged that until hull l0 comes to rest on bottom 30, a portion of the pontoons will continue to remain above the water level, to thereby maintain full stability of the barge structure throughout submergence of hull l0. Once the latter is at rest on bottom it forms a firm foundation for the structure.

With the hull on bottom, the pontoons will now b additionally ballasted until they too sink to the bottom alongside the hull, as illustrated in broken lines in Fig. 9. and the entire load of the structure will now be supported on hull l0. By thus sinking the pontoons to the bottom alongside the hull, they serve the additional valuable function of protecting the land bottom underlying the hull against washing-out at the sides by underwater currents. The tendency for the sand and silt normally forming the underlying land to wash out from under the sides of the barge hull is often aggravated by vibrations due to the drilling operations conducted through the inner, or mid-ship, portion of slot ll. As noted previously, pontoons I! are preferably designed and dimensioned to extend well forward of the inner end of the slot, thus providing protection against washing-out under the most critical area of the barge.

The pontoons, when on bottom, may also be employed to provide additional supporting footings for the barge structure to thereby distribute the load over a greater area and thereby increase the stability of the drilling foundation. This is accomplished by inserting between the upper ends of shafts 28 and suitably positioned crossbracing elements of arm members 25, hydraulic jacks 3| (see Fig. 4a), or some other suitable form of conventional jacking device, and thereby applying pressure to the upper ends of shafts 28 to forcibly thrust pontoons ll against bottom 30. The upward reaction of this force will be exerted through arms 24 to the barge super-structure and will thus transfer a part of the load to the pontoons. Should washing-out occur beneath the pontoons, the stroke of jacks Il may be increased to maintain the downward pressure of the pontoons against bottom 30. The bottom of the pontoons may thus be caused to descend somewhat below the level of the bottom of hull ID, as illustrated in Figs. 4a, 5a and 9, the flush positions of the bottoms of the pontoons being shown in broken lines. By selecting a suitable height for spacers 20, suiilcient clearance may be provided between beams i8 and deck l3 of the hull to permit any desired degree of such additional downward movement of the pontoons relative to hull in. Even before any washing-out may occur at the sides of the hull, jacks 3| may be employed to forcibly drive pontoons ll'l downwardly into the land bottom for some distance below the level of the hull bottom. Thus in addition to supporting a portion of the load, the pontoons will also act as anchors serving to effectively limit any tendency of the main hull to shift over th land bottom.

With the hull and pontoons fully submerged, as described, super-structure I2, because of its open construction, will allow free passage of the waves through the structure and thus eliminate the dangers normally inherent in. presenting a solid surface to the waves and winds prevailing in the open ocean. Furthermore, owing to the very small area of the water plane at the water line, changes in sea level, such as those due to waves and tides, will have very little effect upon the displacement and will not tend to lift the barge during high water or place excessive load on the bottom when the water line drops. It will be understood that super-structure l2 will be constructed of such height as to raise the working platforms Ila and the floor of housing IE to any desired safe height well above any level which it is anticipated will be attained by waves passing through the super-structure, thus providing safe working conditions for the drilling crew.

When the barge structure has been fully submerged and firmly set on bottom, drilling operations may be conducted in the conventional manner, working through slot ll.

Upon completion of the well, the barge structure will be refloated in the following manner: Jacks 3i, if they have been in use, will be removed, freeing the pontoons for upward movement relative to the hull. Ballast will be removed from the pontoons to increase their buoyancy sufficiently to permit the pontoons to rise through the water until pads 23 again come in contact with arms 24. This brings the tops of the pontoons above the water level to the position shown in Fig. 8. Properly proportioned quantities of ballast will now be r moved from both the pontoons and hull In so that both will rise together with the pontoons rising higher above the water as the top of the hull approaches the surface and bearing against arms 24. thus maintaining the stability of the structure while the hull continues to become increasingly buoyant until its upper deck rises above the surface to the position illustrated in Fig. 7, whereupon with the further removal of ballast from the hull, it will again attain its original full floating position, as illustrated in Fig. 6, and the entire structure will be ready for removal to another location. The structure will be withdrawn from the well by pulling it in the aft direction to permit any well pipe or well head connections to exit through the open end of slot II. This operation may be carried out as soon as the bot tom of the barge has left the land bottom and gnome without waiting operation.

From the foregoing, it will be evident that the submergible barge structure and the method in accordance with this invention provides a safe and economical foundation for use in drilling wells in open ocean areas, which may be moved bodily from one location to another with a minimum of effort and expense.

It will be understood that numerous changes and variations may be made in the details of the illustrative embodiments herein described within the scope of the appended claims but without departing from the spirit of this invention.

What I claim and desire to secure by Letters Patent is:

1. A submergible barge structure for water drilling, comprising, a submergible hull section, a pair of submergible pontoon members arranged along opposite sides of said hull section and vertically movable relative thereto, and rigid stop means mounted on said hull section and vertically spaced therefrom engageable with Laid pontoon members to limit the extent of relative vertical movement between said hull section and pontoon members.

2. A submergible barge structure for water for the complete de-watering drilling, comprising, a submergible hull section,

a pair of submengible pontoon members arranged along opposite sides of said hull section connected together across said hull section and vertically movable relative thereto, and stop means mounted on said hull section and vertically spaced therefrom engageable with said pontoon members to limit the extent of relative vertical movement between said hull sction and pontoon members.

3. A submergible barge structure for water drilling, comprising, a submergible hull section, a pair of submergible pontoon members arranged along opposite sides of said hull section and vertically movable relative thereto, and arm members extending laterally from said opposite sides of said hull section and vertically spaced from the upper surface thereof, said arm members being engageable with said pontoon members to limit the extent of relative vertical movement between said hull section and pontoon members.

4. Asubinergibls barge structure for water drilling, comprising a submergible hull section having a longitudinal slot extending inwardly from one end thereof, a pair of elongated pontoon members arranged along opposite sides of said hull section and extending parallel to a substantial portion of the inner end of said slot, and arm members extending laterally from said opposite sides of said hull section and vertically spaced from the upper surface thereof, said arm members being engageable with said pontoon members to limit the extent of relative vertical movement between said hull section and said pontoon members.

5. A submergible barge structure for water drilling, comprising, a submergible hull section, an open-work super-structure mounted on the upper surface of said hull section, a pair of submergible pontoon members arranged along opposite sides of said hull section and vertically movable relative thereto, a plurality of longitudinally spaced beam members extending transversely above the upper surface of said hull section and having their opposite ends rigidly connected to said pontoon members, longitudinally spaced arm members extending laterally from said opposite sides of said super-structure and vertically spaced from the upper surface of said hull section, said arm members being engageable with said pontoon members to limit the extent of relative vertical movement between said hull section and said pontoon members.

6. A submergible barge structure for water drilling, comprising, a submergible hull section, a pair of submergible pontoon members arranged along opposite sides of said hull section and vertically movable relative thereto, arm members extending laterally from said opposite sides of said hull section and vertically spaced from the upper surface thereof, said arm members being engageable with said pontoon members to limit the extent of vertical movement between said hull section and said pontoon members, and vertically adjustable load-supporting elements engageable between said pontoon members and said arm members when -said members are spaced apart. 7. The method of constructing a submerge foundation for a drilling rig for drilling through a water body which comprises the steps of, floating to the drilling location a submergible hull adapted to support a drilling rig thereon, arranging buoyant pontoons along opposite sides of said hull, initiating submergence of said hull relative to said pontoons while constraining relative movement between said pontoons and said hull to substantially only relative vertical movement, transferring at least part of the load of the submerging-hull to said pontoons prior to completion of the submergence of said hull beneath the surface of said water body and while said pontoons are maintained in buoyant condition, and thereafter completing the submergence of said hull to allow the same to sink to the land bottom underlying said water while being stabilized by said pontoons. 8. The method of constructing a submerged foundation for a drilling rig for drilling through a water body which comprises the steps of, floating on said water body to the drilling location a submergible hull adapted to support a drilling rig thereon, arranging buoyant pontoons along opposite sides of said hull, initiating submergence of said hull relative to said pontoons while constraining relative movement between said pontoons and said hull to substantially only relative vertical movement, transferring at least a portion of the load of the submerging hull to said pontoons prior to completion of the submergence of said hull beneath the surface of said water body and while said pontoons are maintained in buoyant condition, and thereafter partially reducing the buoyancy of said pontoons suihciently to complete the submergence of said hull and to allow the same to sink to the land bottom underlying said water body.

9. The method of constructing a submerged foundation for a drilling rig for drilling through a water body which comprises the steps of, floating on said water body to the drilling location a submergible hull adapted to support a drilling rig thereon, arranging buoyant pontoons along opposite sides of said hull, initiating submergence of said hull relative to said pontoons while constraining relative movement between said pontoons and said hull to substantially only relative vertical movement, transferring at least a portion of the load of the submerging hull to said pontoons prior to completion of the submergence of said hull beneath the surface of said water body and while said pontoons are maintained in buoyant condition, thereafter partially reducing the buoyancy of said pontoons sufficiently to complete the submergence of said hull and to allow the same to sink to the land bottom underlying said water body, and subsequently reversing said steps to refloat said hull.

10. The method of constructing a submerged foundation for a drilling rig for drilling through a water body which comprises the steps of, floating on said water body to the drilling location a submergible hull adapted to support a drilling rig thereon, arranging buoyant pontoons along opposite sides of said hull, initiating submergence of said hull relative to said pontoons while constraining relative movement between said pontoons and said hull to substantially only relative vertical movement, transferring at least a portion of the load of the submerging hull to said pontoons prior to completion of submergence of said hull beneath the surface of said water body and while said pontoons are maintained in buoyant condition, thereafter partially reducing the buoyancy of said pontoons sufficiently to complete the submergence of said hull and to allow the same to sink to the land bottom underlying said water body, and thereafter sinking said pontoons to said land bottom alongside said hull.

11. The method of constructing a submerged foundation for a drilling rig for drilling through a water body which comprises the steps of, floating on said water body to the drilling location a. submergible hull adapted to support a drilling rig thereon, arranging buoyant pontoons along opposite sides of said hull, initiating submergence of said hull relative to said pontoons while constraining relative movement between said pontoons and said hull to substantially only relative vertical movement, transferring at least a portion of the load of the submerging hull to said pontoons prior to completion of submergence of said hull beneath the surface of said water body and while said pontoons are maintained in buoyant condition, thereafter partially reducing the buoyancy of said pontoons sudiciently to complete the submergence of said hull and to allow the same to sink to the land bottom underlying said water body, thereafter sinking said pontoons to said land bottom alongside side said hull, and subsequently reversing said steps to reiloat said pontoons and said hull.

12. The method of constructing a submerged foundation for a drilling rig for drilling through a water bod comprising the steps of, floating on said water body to the drilling location a submergible hull adapted to support a drilling rig thereon, arranging buoyant pontoons along opposite sides of said hull, initiating submergence of said hull relative to said pontoons while constraining relative movement between said pontoons and said hull to substantially only relative vertical movement, transferring at least a portion of the load of the submerging hull to said pontoons priorto completion of submergence of said hull beneath the surface of said water body and while said pontoons are maintained in buoyant condition, thereafter partially reducing the buoyancy of said pontoons sufllciently to complete the submergence of said hull and to allow the same to sink to the land bottom underlying said water body, subsequently sinking said pontoons to said land bottom alongside said hull, and thereafter re-transferring a portion of the load from said hull to said pontoons.

13. The method of constructing a submerge foundation for a drilling rig for drilling through a water body which comprises the steps of. floating to the drilling location a submergible hull adapted to support a drilling rig thereon, arranging buoyant pontoons along opposite sides of said hull. initiating submergence of said hull relative to said pontoons while constraining relative movement between said pontoons and said hull to substantially only relative vertical movement, transferring at least part of the load of the submerging hull to said pontoons prior to completion of the submergence of said hull beneath the surface of said water body and while said pontoons are maintained in buoyant condition, thereafter completing the submergence of said hull to allow the same to sink to the land bottom underlying said water while being stabilized by said pontoons, thereafter sinking said pontoons to the land bottom alongside said hull, and finally forcing said pontoons into the land bottom for a distance below the level of the bottom of said hull.

14. A submergible barge structure for water drilling, comprising, a submergible hull section, a pair of submergible pontoon members arranged along opposite sides of said hull section and vertically movable relative thereto, rigid stop means mounted on said hull section and vertically spaced therefrom engageable with said pontoon members to limit the extent of relative vertical movement between said hull section and said pontoon members, and an adjustable thrust connection extending between said pontoon members and a portion of said hull section vertically spaced therefrom for applying a portion of the load of said hull section downwardly on said pontoon members.

15. A submergible barge structure for water drilling, comprising, a submergible hull section, a pair of submergible pontoon members arranged along opposite sides of said hull section, vertically slidahle connection members arranged between said hull section and said pontoon members adapted to constrain movement therebetween to substantially only relative vertical movement, and rigid stop means mounted on said hull section and vertically spaced therefrom engageable with said pontoon members to limit the extent of relative vertical movement between said hull section and said pontoon members.

16, A submergible barge structure for water drilling, comprising, a submergible hull section, a pair of submergible pontoon members arranged along opposite sides of said hull section and vertically movable relative thereto, the inner walls of said pontoon members sloping downwardly and outwardly relative to the adjacent sides of said hull section. and rigid stop means mounted on said hull section and vertically spaced therefrom engageable with said pontoon members to limit the extent of relative vertical movement between said hull section and pontoon members.

JOHN T. HAYWARD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,581,533 Giliiano Aug. 121, 1928 2,327,118 MacKnight M, Aug. 17, 5343 2,422,168 Kirby June it, till! 

